Otitis media is responsible for substantial human suffering, the most common reason for pediatric physician visits and antibiotic prescriptions to children, and the cause of over $5 billion in health care expenses annually. Initial infection by bacterial pathogens including non-typeable Haemophilus influenzae (NTHi) is believed to contribute to most otitis media. Bacterial infection directly provokes pain and conductive hearing loss by stimulating mucus overproduction in the middle ear. Mucus is largely the product of mucin glycoproteins including MUC5AC, which is strongly upregulated by bacterial infection. The signaling pathways through which NTHi induces MUC5AC are relatively well-characterized. In contrast, signaling pathways through which NTHi-induced MUC5AC expression is down-regulated remain essentially unknown. The goal of this proposed study is to examine the role of CYLD, the cylindromatosis tumor supressor, in regulating MUC5AC expression in the context of NTHi-induced otitis media. CYLD is a deubiquitinase enzyme shown to negatively regulate multiple signaling pathways, including the p38 pathway principally involved in MUC5AC upregulation. We therefore hypothesize that CYLD negatively regulates NTHi-induced MUC5AC expression by deubiquitinating TRAF6 and/or TRAF7, signaling intermediates of the p38 pathway. By elucidating how mucus production is down-regulated, we will facilitate the development of novel therapeutics that reduce mucus overproduction in the middle ear and thereby ameliorate the symptoms and sequelae of otitis media. Using multiple molecular and cell biology techniques, we will: 1. Investigate the inhibitory effect of CYLD on NTHi-induced MUC5AC expression in models of otitis media in vitro and in vivo. 2. Identify the molecular targets of CYLD involved in the CYLD-mediated regulation of NTHi-induced MUC5AC expression in vitro and in vivo. 3. Determine the molecular mechanism through which CYLD regulates NTHi-induced MUC5AC expression. Ear infections are the number one reason for visits to pediatricians and antibiotic prescriptions to children, and a major cause of human suffering. Excess mucus production triggered by bacterial infection leads to pain and short- and long-term hearing problems during ear infections. Understanding how mucus production is controlled in the middle ear will lay the foundation for new drugs that decrease mucus production and make ear infections less harmful. [unreadable] [unreadable] [unreadable]